Effects of Irradiation Creep on Ex-Reactor Mechanical Properties

Irradiation creep of reactor core components is usually considered nondamaging. This concept has had no experimental verification, reducing confidence in its application to reactor design. The work reported herein was intended to test the damaging nature of irradiation creep. Material used was 20 percent cold-worked AISI 316 stainless steel tubing of 5.84-mm outside diameter and 5.08-mm inside diameter. The tubing specimens had been irradiated with stress and with zero stress to provide varying amounts of irradiation creep. A transient burst test was used to assess creep effects. This test imposes a constant stress and an increasing constant rate temperature ramp on a tubular specimen until rupture occurs. Results demonstrated that the specimens with irradiation creep failed at temperatures similar to those without irradiation creep, indicating comparable cladding strengths. Strain results were less clear, but no major reductions were seen. Thus, irradiation creep to the magnitudes investigated was nondamaging.